1. Field of the Invention
This invention relates to a power output device with a fuel cell and a method of outputting power.
2. Description of Related Art
A device, which is mounted on a vehicle and limits an actual output of a fuel cell according to a required output calculated from a position of an accelerator pedal, has been suggested (for example, Japanese Patent Laid-Open Publication No. 7-75214). The device alters operating conditions of the fuel cell according to the required output, and performs a control to secure that the required output is outputted from the fuel cell. When the possible output of the fuel cell is less than the required output, the device limits the actual output to the possible output to prevent damage to the fuel cell.
However, with the above-mentioned art, a sense of discomfort may be given to an operator when the device is operated. When the required output from the operator is larger than the possible output of the fuel cell, the actual output is limited to the possible output of the fuel cell. Therefore, the operator has to conclude, from experience, that the required output is not available, whether by a failure in the power output device or the fuel cell not reaching normal operating conditions. If the operator uses the same power output device periodically, he or she can come to an appropriate conclusion. However, if the operator does not periodically use the power output device, it is difficult to come to an appropriate conclusion.